Privacy and civil rights groups lauded Wednesday's unanimous U.S. Supreme Court ruling that police must obtain a search warrant before searching through the contents of an arrested person's cellphone.

"We cannot deny that our decision today will have an impact on the ability of law enforcement to combat crime," Chief Justice John Roberts acknowledged. But privacy comes at a cost, he added.

Several groups said the ruling was pivotal and had far-reaching implications.

Alan Butler, appellate advocacy counsel for the Electronic Privacy Information Center (EPIC), one of several groups that filed an amicus brief in the case, said the rulings affirm Fourth Amendment protections in the digital age.

"This is a hugely important decision. The big takeaway here is that the court recognizes that digital data is very different from its physical analogues," Butler said.

Today's ruling makes it clear that cellphones and other electronic devices need to be treated differently, Butler said.

"We expected the court would ultimately rule in our favor but never expected a unanimous opinion. This is a pivotal moment for the Fourth Amendment," he said

The Supreme Court decision follows myriad contrasting rulings by various courts across the country, noted Hanni Fakhoury, staff attorney at the Electronic Frontier Foundation. "Creating a bright line rule gives the public and the police clear guidance," Fakhoury said.

The Supreme Court recognizes that smartphones are essentially miniature computers with enormous amounts of data that travels wherever users go, he said. "That recognition will have important implications for future legal challenges concerning the government's use of technology, whether it be cellphone tracking, Stingrays or NSA surveillance," Fakhoury said.

The Supreme Court ruling held that mobile phones are different from wallets, purses, cigarette packages or other objects held by suspects who have been apprehended. Searching through the contents of a cellphone is different from searching other things, Roberts wrote.

To argue that the two acts are similar "is like saying a ride on horseback is materially indistinguishable from a flight to the moon. Both are ways of getting from point A to point B, but little else justifies lumping them together," he wrote. "Modern cell phones are not just another technological convenience. With all they contain and all they may reveal, they hold for many Americans 'the privacies of life.'"

Smartphones, for example, can store huge amounts of text, pictures and video. They collect, in one place, different types of information that "reveal much more in combination than any isolated record," the ruling said.

"A decade ago, officers might have occasionally stumbled across a highly personal item such as a diary, but today many of the more than 90% of American adults who own cell phones keep on their person a digital record of nearly every aspect of their lives," Roberts said.

The court also noted that user data and records could be stored in the cloud on servers outside the user's control -- another reason why search warrants should be required, the court held.

One of the two cases reviewed by the court involved David Riley, who was stopped by police in San Diego in 2009 for a traffic violation. He was later arrested on a gang-related charge based on information gathered from his cellphone. A trial court convicted Riley, rejecting his argument that the evidence against him was gathered without a warrant, and thus illegally. A California appellate court later affirmed the trial court verdict.

The second case involved Brima Wurie, who was arrested by Boston police in 2007. After the arrest, police searched through the logs of Wurie's mobile phone and traced a number that was repeatedly calling the device to his home.

Police then obtained a search warrant and found guns and ammunition in Wurie's home. Wurie was convicted after a District Court rejected his appeal to throw out evidence found on his cellphone because it was gathered without a warrant.

The First Circuit Court of Appeals agreed with Wurie and vacated the conviction, prompting the state to appeal to the Supreme Court.